9.2.2 RMI Connector Client

The RMI connector Client example is shown in Example 9–3.

Example 9–3 RMI Connector Client

public class Client { 
 
  public static void main(String[] args) { 
    try { 
      // Create an RMI connector client 
      // 
      JMXServiceURL url = new JMXServiceURL( 
         "service:jmx:rmi:///jndi/rmi://localhost:9999/server"); 
      JMXConnector jmxc = JMXConnectorFactory.connect(url, null); 
      MBeanServerConnection mbsc = jmxc.getMBeanServerConnection(); 
       
      // Get domains from MBeanServer 
      // 
      String domains[] = mbsc.getDomains(); 
      for (int i = 0; i < domains.length; i++) { 
          System.out.println("Domain[" + i + "] = " + domains[i]); 
      } 
 
      String domain = mbsc.getDefaultDomain();       
   
      // Create SimpleStandard MBean and perform simple MBean operations 
      // 
      ObjectName mbeanName =  
             new ObjectName("MBeans:type=SimpleStandard"); 
      mbsc.createMBean("SimpleStandard", mbeanName, null, null); 
      System.out.println("\nMBean count = " + mbsc.getMBeanCount()); 
      System.out.println("\nState = " + 
             mbsc.getAttribute(mbeanName, "State")); 
      mbsc.setAttribute(mbeanName, 
             new Attribute("State", "changed state")); 
             
      SimpleStandardMBean proxy = (SimpleStandardMBean) 
          MBeanServerInvocationHandler.newProxyInstance( 
                                       mbsc, 
                                       mbeanName, 
                                       SimpleStandardMBean.class, 
                                       false); 
      System.out.println("\nState = " + proxy.getState()); 
 
      ClientListener listener = new ClientListener(); 
      mbsc.addNotificationListener(mbeanName, listener, null, null); 
 
      mbsc.invoke(mbeanName, "reset", null, null); 
 
      mbsc.removeNotificationListener(mbeanName, listener); 
      mbsc.unregisterMBean(mbeanName); 
      jmxc.close(); 
    } catch (Exception e) {      e.printStackTrace(); 
    } 
  } 
} 

In this example, the Client creates an RMI connector client that is configured to connect to the RMI connector server created by Server in 9.1.2 RMI Connector Server.

As you can see, the Client defines the same service URL url as that defined by Server. This allows the connector client to retrieve the RMI connector server stub named server from the RMI registry running on port 9999 of the local host, and to connect to the RMI connector server.

With the RMI registry thus identified, the connector client can be created. The connector client, jmxc, is an instance of the JMX Remote API interface JMXConnector, created by the connect() method of JMXConnectorFactory. The connect() method is passed the parameters url and a null environment map when it is called.

An instance of MBeanServerConnection, named mbsc, is then created by calling the getMBeanServerConnection() method of the JMXConnector instance jmxc.

The connector client is now connected to the MBean server created by Server, and can create MBeans and perform operations on them with the connection remaining completely transparent to both ends.

In the examples directory, there is an MBean interface and a class to define an MBean called SimpleStandard. As the name suggests, this is a very basic MBean of the type described in Chapter 1, Standard MBeans. The connector client creates an instance of this SimpleStandard MBean and registers it in the MBean server with a call to the createMBean() method of MBeanServerConnection. The client then activates notifications by calling addNotificationListener(), and performs the operations defined by SimpleStandard as if they were local MBean operations.

Finally, the client unregisters the SimpleStandard MBean and closes the connection.